The Experts below are selected from a list of 168 Experts worldwide ranked by ideXlab platform
Anthony Guiseppi-elie - One of the best experts on this subject based on the ideXlab platform.
-
Responsive Polymers in the Fabrication of Enzyme-Based Biosensors
Biomaterials Science, 2020Co-Authors: John R. Aggas, Anthony Guiseppi-elieAbstract:Abstract Polymers play a crucial role in the design, fabrication, and performance of enzyme-based biosensors. Critical roles include (1) bioconjugation/bioimmobilization, (2) biohosting, (3) biocompatibility to reduce biofouling, and (4) active transduction. The latter role of polymers as a transducer-active or stimuli-responsive component of the Biotransducer of a biosensor has not been subject to critical review. Among the several polymers used are inherently conductive polymers (ICPs), responsive-hydrogels, polymeric redox-mediators, ferroelectric, piezoelectric, and pyroelectric polymers. Additionally, polymeric composites comprise an inert polymeric binder and a conductive inclusion such as ICP filers and carbonaceous materials (dots, tubes, sheets). The classic biosensor system is discussed, with a focus on roles of these polymers within the four main types of electrochemical biosensors (amperometric, conductometric, impedimetric, potentiometric). Both passive (physical support) and active roles of responsive polymers within electrochemical biosensors are explored. Integration of responsive polymers in active roles in electrochemical biosensor systems has enabled dual- and multistimuli responsive biosensors capable of responses elicited by physical, chemical, or biological stimuli. Biosensor fabrication methods including microlithography and 3-D printing utilize existing technologies originally designed for inorganic materials to render bioactive, 4-D responsive biosensor electrodes. The pairing of new electrode architectures and chemistries including conjugation with carbon nanotubes, enzyme active site conjugation by boric acid, and direct molecular wiring has led to the development toward rapid, selective, miniaturized glucose sensors, leaving development toward wireless implantable biosensors an achievable goal.
-
Nanobiosensing with graphene and carbon quantum dots: Recent advances
Materials Today, 2020Co-Authors: Brandon K. Walther, Cerasela Zoica Dinu, Dirk M. Guldi, Vladimir G. Sergeyev, Stephen E. Creager, John P. Cooke, Anthony Guiseppi-elieAbstract:Abstract Graphene and carbon quantum dots (GQDs and CQDs) are relatively new nanomaterials that have demonstrated impact in multiple different fields thanks to their unique quantum properties and excellent biocompatibility. Biosensing, analyte detection and monitoring wherein a key feature is coupled molecular recognition and signal transduction, is one such field that is being greatly advanced by the use of GQDs and CQDs. In this review, recent progress on the development of Biotransducers and biosensors enabled by the creative use of GQDs and CQDs is reviewed, with special emphasis on how these materials specifically interface with biomolecules to improve overall analyte detection. This review also introduces nano-enabled Biotransducers and different biosensing configurations and strategies, as well as highlights key properties of GQDs and CQDs that are pertinent to functional Biotransducer design. Following relevant introductory material, the literature is surveyed with emphasis on work performed over the last 5 years. General comments and suggestions to advance the direction and potential of the field are included throughout the review. The strategic purpose is to inspire and guide future investigations into biosensor design for quality and safety, as well as serve as a primer for developing GQD- and CQD-based biosensors.
-
Fabrication and in vitro performance of a dual responsive lactate and glucose biosensor
Electrochimica Acta, 2018Co-Authors: Christian N. Kotanen, Olukayode Karunwi, Fouzan Alam, Catherine F. T. Uyehara, Anthony Guiseppi-elieAbstract:Abstract Implantable multi-analyte biosensors are particularly challenging because the specificity of bioreceptors must be conferred to limited real estate. Additive biofabrication techniques based on electropolymerization for a dual responsive (glucose and lactate) Biotransducer have been developed and characterized in vitro. Mediator modification of working microdisc electrode arrays with nickel hexacyanoferrate (NiHCF) followed by alternating layer-by-layer electropolymerization of polypyrrole-poly(styrene-sulfonic acid) (PPy-PSSA) and PPy-Enzyme (glucose oxidase or lactate oxidase) to a total applied charge density (QT = 50 or 100 mC/cm2 applied in Q = 5, 10 or 100 mC/cm2 increments) were evaluated for their contributions to a biosensor's bioanalytical performance. Single layered PPy-Enzyme (100 mC/cm2) Biotransducers showed a higher sensitivity compared to all multi-layered Biotransducers. An interceding layer of NiHCF at the Pt|PPy-GOx interface improved consistency in PPy-GOx electrodeposition compared to unmodified devices but, measured under self-consistent anodic conditions (0.65 V vs. Ag/AgCl), did not improve sensitivity. Electrochemical Impedance Spectroscopy (EIS) showed that the mediator layer did not change the overall impedance spectra of the Pt microelectrode array when compared to unmodified Pt electrodes. Under anodic test conditions, non-mediator modified devices had a higher sensitivity (0.94 nA/mM) to glucose than the mediator modified devices (0.32 nA/mM).
-
Microfabricated biosensor for the simultaneous amperometric and luminescence detection and monitoring of Ochratoxin A.
Biosensors and Bioelectronics, 2016Co-Authors: Scherrine A. Tria, David Lopez-ferber, Catherine Gonzalez, Ingrid Bazin, Anthony Guiseppi-elieAbstract:The low molecular weight hapten, Ochratoxin A (OTA), is a natural carcinogenic mycotoxin produced by Aspergillus and Penicillium fungi and so it commonly appears in wines, other foods, and in the environment. An amperometric biosensor has been developed that uses the immobilized synthetic peptide, NFO4; which possesses a high binding affinity and thus provides for molecular recognition of OTA; simulating the mycotoxin-specific antibody. Biotransducers were produced from a microlithographically fabricated electrochemical cell-on-a-chip that uses the microdisc electrode array working electrode format augmented with microporous graphitized carbon (MGC) that was electrodeposited within a poly(aniline-co-meta-aminoaniline) electroconductive polymer layer. A redox mediator, iron-nickel hexacyanoferrate (Fe|NiHCF) was amperometrically deposited onto the MGC. The device was then dip-coated with monomer cocktail that yielded poly(HEMA-co-AEMA) foam that was prepared in-situ by UV crosslinking and by sequentially freezing followed by freeze drying of the chip to yield a 3-D support for the chelation of Zn(2+) ions (ZnCl2) and the subsequent immobilization of N-terminus his-tagged peptide, NFO4. To conduct the biosensors assay, HRP conjugated OTA was added to the free OTA solutions and together competitively incubated on the biospecific MDEA ECC 5037-Pt|MGC|HCF|Hydrogel-NFO4 Biotransducer. The amperometric response to peroxide was determined after 5 min of enzymatic reaction following addition of standard substrate H2O2/luminol. Simultaneous analysis of light emission signals (λmax=425 nm) allowed direct comparison of amperometric and luminescence performance. Using chitosan foam and a luminescence bioassay we obtained maximum inhibition at 10 μg L(-1) and half inhibition occurred at 2.1 μg L(-1). Using poly(HEMA-co-AEMA) hydrogel and an amperometric bioassay (50s) we obtained maximum inhibition at 10 μg L(-1) and half inhibition occurred at 2.8 μg L(-1).
-
Biofabrication Using Pyrrole Electropolymerization for the Immobilization of Glucose Oxidase and Lactate Oxidase on Implanted Microfabricated Biotransducers
Bioengineering, 2014Co-Authors: Christian N. Kotanen, Olukayode Karunwi, Anthony Guiseppi-elieAbstract:The dual responsive Electrochemical Cell-on-a-Chip Microdisc Electrode Array (ECC MDEA 5037) is a recently developed electrochemical transducer for use in a wireless, implantable biosensor system for the continuous measurement of interstitial glucose and lactate. Fabrication of the biorecognition membrane via pyrrole electropolymerization and both in vitro and in vivo characterization of the resulting Biotransducer is described. The influence of EDC-NHS covalent conjugation of glucose oxidase with 4-(3-pyrrolyl) butyric acid (monomerization) and with 4-sulfobenzoic acid (sulfonization) on biosensor performance was examined. As the extent of enzyme conjugation was increased sensitivity decreased for monomerized enzymes but increased for sulfonized enzymes. Implanted Biotransducers were examined in a Sprague-Dawley rat hemorrhage model. Resection after 4 h and subsequent in vitro re-characterization showed a decreased sensitivity from 0.68 (±0.40) to 0.22 (±0.17) µA·cm−2·mM−1, an increase in the limit of detection from 0.05 (±0.03) to 0.27 (±0.27) mM and a six-fold increase in the response time from 41 (±18) to 244 (±193) s. This evidence reconfirms the importance of biofouling at the bio-abio interface and the need for mitigation strategies to address the foreign body response.
Emmanuel I. Iwuoha - One of the best experts on this subject based on the ideXlab platform.
-
Tin Selenide Quantum Dots Electrochemical Biotransducer for the Determination of Indinavir - A Protease Inhibitor Anti-Retroviral Drug
Journal of Nano Research, 2016Co-Authors: Usisipho Feleni, Abongile M. Jijana, Priscilla G. L. Baker, Rachel Fanelwa Ajayi, Unathi Sidwaba, Samantha F. Douman, Emmanuel I. IwuohaAbstract:Biocompatibility of tin selenide quantum dots was achieved by the incorporation of 3-mercaptopropionic acid (3-MPA) as a capping agent, which also improved the stability and the solubility of the material. The UV-Vis spectrophotometric analysis of the quantum dots revealed a broad absorption band at ~ 330 nm (with a corresponding band gap, Eg, value of 3.75 eV), which is within the range of values expected for quantum dots materials. The 3-mercaptopropionic acid-capped tin selenide (3-MPA-SnSe) quantum dots were used to develop an electrochemical biosensor for indinavir, which is a protease inhibitor antiretroviral (ARV) drug. The biosensor was prepared by the self-assembly of L-cysteine on a gold electrode that was functionalised with 3-MPA-SnSe quantum dots, followed by cross-linking with cytochrome P450-3A4 (CYP3A4) using 1-ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The electrocatalytic properties of the biosensor included a characteristic cyclic voltammetric reduction peak at-380 mV, which was used to detect the response of the biosensor to indinavir. The sensor performance parameters included response time and limit of detection (LOD) values of 11 s and 3.22 pg/mL, respectively. The test concentration range studied (0.014 – 0.066 ng/mL) gave a linear calibration plot for indinavir, and it was lower than the physiological plasma concentration index (i.e. maximum plasma concentrations, Cmax,) of indinavir (5 - 15 ng/mL) normally observed 8 h after intake. This indicates that the biosensor can be very useful in the case of ultra-rapid metabolisers where very low Cmax values are expected
-
Tin Selenide Quantum Dots Electrochemical Biotransducer for the Determination of Indinavir - A Protease Inhibitor Anti-Retroviral Drug
Journal of Nano Research, 2016Co-Authors: Usisipho Feleni, Abongile M. Jijana, Rachel Fanelwa Ajayi, Unathi Sidwaba, Samantha F. Douman, Priscilla Gloria Lorraine Baker, Emmanuel I. IwuohaAbstract:Biocompatibility of tin selenide quantum dots was achieved by the incorporation of 3-mercaptopropionic acid (3-MPA) as a capping agent, which also improved the stability and the solubility of the material. The UV-Vis spectrophotometric analysis of the quantum dots revealed a broad absorption band at ~ 330 nm (with a corresponding band gap, Eg, value of 3.75 eV), which is within the range of values expected for quantum dots materials. The 3-mercaptopropionic acid-capped tin selenide (3-MPA-SnSe) quantum dots were used to develop an electrochemical biosensor for indinavir, which is a protease inhibitor antiretroviral (ARV) drug. The biosensor was prepared by the self-assembly of L-cysteine on a gold electrode that was functionalised with 3-MPA-SnSe quantum dots, followed by cross-linking with cytochrome P450-3A4 (CYP3A4) using 1-ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The electrocatalytic properties of the biosensor included a characteristic cyclic voltammetric reduction peak at-380 mV, which was used to detect the response of the biosensor to indinavir. The sensor performance parameters included a response time and sensitivity values of 11 s and 0.221 μA/nM, respectively. The test concentration range studied (0.014 – 0.066 ng/mL) gave a linear calibration plot for indinavir, and it was lower than the physiological plasma concentration index (i.e. maximum plasma concentrations, Cmax,) of indinavir (5 - 15 ng/mL) normally observed 8 h after intake. This indicates that the biosensor can be very useful in the case of ultra-rapid metabolisers where very low Cmax values are expected
-
3-Mercaptopropionic acid capped ZnSe quantum dot-cytochrome P450 3A4 enzyme Biotransducer for 17β-estradiol
Journal of Electroanalytical Chemistry, 2011Co-Authors: Peter M. Ndangili, Abongile M. Jijana, Priscilla G. L. Baker, Emmanuel I. IwuohaAbstract:Abstract A 3-mercaptopropionic acid capped ZnSe quantum dot/cytochrome P450 3A4 enzyme electrochemical Biotransducer for 17β-estradiol (endocrine disrupting compound) is presented. The Biotransducer combines both the electric and chemical properties of 3-mercaptopropionic acid capped ZnSe quantum dots as well as redox and binding affinity properties of the cytochrome P450 3A4 enzyme to steroids. 3-mercaptopropionic acid capped ZnSe quantum dots were conjugated to gold electrode, previously modified with self-assembled l -cysteamine. Cytochrome P450 3A4 enzyme was then conjugated onto the modified gold electrode for 3 h. A Fourier transform infrared spectra of this Biotransducer showed a band at 2956 cm−1, confirming the formation of a secondary amide bond from free carboxylic groups on the ZnSe quantum dots surface and amine groups on the cytochrome P450 3A4 enzyme. The Biotransducer showed proportional increase in current with increasing concentration of 17β-estradiol in a phosphate buffer under aerobic conditions. A high sensitivity (1.08 × 10−5 A μM−1) and a low Michaelis–Menten constant ( K m app = 0.15 mM ) obtained for this Biotransducer confirms that the cytochrome P450 3A4 was immobilized in a biocompatible microenvironment, retained its catalytic properties and exhibited high enzymatic activity towards 17β-estradiol. The detection limit was 1.03 × 10−10 mol L−1.
James R Wild - One of the best experts on this subject based on the ideXlab platform.
-
The development of a new biosensor based on recombinant E. coli for the direct detection of organophosphorus neurotoxins.
Biosensors and Bioelectronics, 1998Co-Authors: Evguenia I Rainina, E N Efremenco, Aleksandr L Simonian, S D Varfolomeyev, James R WildAbstract:A new biosensor for the direct detection of organophosphorus (OP) neurotoxins has been developed utilizing cryoimmobilized, recombinant E. coli cells capable of hydrolyzing a wide spectrum of OP pesticides and chemical warfare agents. The biological transducer was provided by the enzymatic hydrolysis of OP neurotoxins by organophosphate hydrolase which generates two protons through a reaction in which P-O, P-F, P-S or P-CN bonds are cleaved, and the proton release corresponded with the quantity of organophosphate hydrolyzed. This stoichiometric relationship permitted the creation of a potentiometric biosensor for detection of OP neurotoxins and a pH-based assay was developed as a direct function of the concentration of OP neurotoxins and the immobilized biomass. In these studies utilizing paraoxon as the substrate, neurotoxin concentration was determined with two different types of measuring units containing immobilized cells: (1) a stirred batch reactor; and (2) a flow-through column minireactor. A pH glass electrode was used as the physical transducer. The linear detection range for paraoxon spanned a concentration range of 0.25-250 ppm (0.001-1.0 mM). The response times were 10 min for the batch reactors and 20 min for the flow-through systems. It was possible to use the same biocatalyst repetitively for 25 analyses with a 10 min intermediate washing of the biocatalyst required for reestablishing the starting conditions. The cryoimmobilized E. coli cells exhibited stable hydrolytic activity for over 2 months under storage in 50 mM potassiumphosphate buffer at +4 degrees C and provide the potential for the development of a stable Biotransducer for detecting various OP neurotoxins.
-
the development of a new biosensor based on recombinant e coli for the direct detection of organophosphorus neurotoxins
Biosensors and Bioelectronics, 1996Co-Authors: Evguenia I Rainina, E N Efremenco, Aleksandr L Simonian, S D Varfolomeyev, James R WildAbstract:Abstract A new biosensor for the direct detection of organophosphorus (OP) neurtoxins has been developed utilizing cryoimmobilized, recombinant E. coli cells capable of hydrolyzing a wide spectrum of OP pesticides and chemical warfare agents. The biological transducer was provided by the enzymatic hydrolysis of OP neurotoxins by organophosphate hydrolase which generates two protons through a reaction in which PO, PF, PS or PCN bonds are cleaved, and the proton release corresponded with the quantity of organophosphate hydrolyzed. This stoichiometric relationship permitted the creation of a potentiometric biosensor for detection of OP neurotoxins and a pH-based assay was developed as a direct function of the concentration of OP neurotoxins and the immobilized biomass. In these studies utilizing paraoxon as the substrate, neurotoxin concentration was determined with two different types of measuring units containing immobilized cells: (1) a stirred batch reactor; and (2) a flow-through column minireactor. A pH glass electrode was used as the physical transducer. The linear detection range for paraoxon spanned a concentration range of 0.25–250 ppm (0.001–1.0 mM). The response times were 10 min for the batch reactors and 20 min for the flow-through systems. It was possible to use the same biocatalyst repetitively for 25 analyses with a 10 min intermediate washing of the biocatalyst required for reestablishing the starting conditions. The cryoimmobilized E. coli cells exhibited stable hydrolytic activity for over 2 months under storage in 50 mM potassium-phosphate buffer at +4°C and provide the potential for the development of a stable Biotransducer for detecting various OP neurotoxins.
Usisipho Feleni - One of the best experts on this subject based on the ideXlab platform.
-
Tin Selenide Quantum Dots Electrochemical Biotransducer for the Determination of Indinavir - A Protease Inhibitor Anti-Retroviral Drug
Journal of Nano Research, 2016Co-Authors: Usisipho Feleni, Abongile M. Jijana, Priscilla G. L. Baker, Rachel Fanelwa Ajayi, Unathi Sidwaba, Samantha F. Douman, Emmanuel I. IwuohaAbstract:Biocompatibility of tin selenide quantum dots was achieved by the incorporation of 3-mercaptopropionic acid (3-MPA) as a capping agent, which also improved the stability and the solubility of the material. The UV-Vis spectrophotometric analysis of the quantum dots revealed a broad absorption band at ~ 330 nm (with a corresponding band gap, Eg, value of 3.75 eV), which is within the range of values expected for quantum dots materials. The 3-mercaptopropionic acid-capped tin selenide (3-MPA-SnSe) quantum dots were used to develop an electrochemical biosensor for indinavir, which is a protease inhibitor antiretroviral (ARV) drug. The biosensor was prepared by the self-assembly of L-cysteine on a gold electrode that was functionalised with 3-MPA-SnSe quantum dots, followed by cross-linking with cytochrome P450-3A4 (CYP3A4) using 1-ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The electrocatalytic properties of the biosensor included a characteristic cyclic voltammetric reduction peak at-380 mV, which was used to detect the response of the biosensor to indinavir. The sensor performance parameters included response time and limit of detection (LOD) values of 11 s and 3.22 pg/mL, respectively. The test concentration range studied (0.014 – 0.066 ng/mL) gave a linear calibration plot for indinavir, and it was lower than the physiological plasma concentration index (i.e. maximum plasma concentrations, Cmax,) of indinavir (5 - 15 ng/mL) normally observed 8 h after intake. This indicates that the biosensor can be very useful in the case of ultra-rapid metabolisers where very low Cmax values are expected
-
Tin Selenide Quantum Dots Electrochemical Biotransducer for the Determination of Indinavir - A Protease Inhibitor Anti-Retroviral Drug
Journal of Nano Research, 2016Co-Authors: Usisipho Feleni, Abongile M. Jijana, Rachel Fanelwa Ajayi, Unathi Sidwaba, Samantha F. Douman, Priscilla Gloria Lorraine Baker, Emmanuel I. IwuohaAbstract:Biocompatibility of tin selenide quantum dots was achieved by the incorporation of 3-mercaptopropionic acid (3-MPA) as a capping agent, which also improved the stability and the solubility of the material. The UV-Vis spectrophotometric analysis of the quantum dots revealed a broad absorption band at ~ 330 nm (with a corresponding band gap, Eg, value of 3.75 eV), which is within the range of values expected for quantum dots materials. The 3-mercaptopropionic acid-capped tin selenide (3-MPA-SnSe) quantum dots were used to develop an electrochemical biosensor for indinavir, which is a protease inhibitor antiretroviral (ARV) drug. The biosensor was prepared by the self-assembly of L-cysteine on a gold electrode that was functionalised with 3-MPA-SnSe quantum dots, followed by cross-linking with cytochrome P450-3A4 (CYP3A4) using 1-ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The electrocatalytic properties of the biosensor included a characteristic cyclic voltammetric reduction peak at-380 mV, which was used to detect the response of the biosensor to indinavir. The sensor performance parameters included a response time and sensitivity values of 11 s and 0.221 μA/nM, respectively. The test concentration range studied (0.014 – 0.066 ng/mL) gave a linear calibration plot for indinavir, and it was lower than the physiological plasma concentration index (i.e. maximum plasma concentrations, Cmax,) of indinavir (5 - 15 ng/mL) normally observed 8 h after intake. This indicates that the biosensor can be very useful in the case of ultra-rapid metabolisers where very low Cmax values are expected
Christian N. Kotanen - One of the best experts on this subject based on the ideXlab platform.
-
Fabrication and in vitro performance of a dual responsive lactate and glucose biosensor
Electrochimica Acta, 2018Co-Authors: Christian N. Kotanen, Olukayode Karunwi, Fouzan Alam, Catherine F. T. Uyehara, Anthony Guiseppi-elieAbstract:Abstract Implantable multi-analyte biosensors are particularly challenging because the specificity of bioreceptors must be conferred to limited real estate. Additive biofabrication techniques based on electropolymerization for a dual responsive (glucose and lactate) Biotransducer have been developed and characterized in vitro. Mediator modification of working microdisc electrode arrays with nickel hexacyanoferrate (NiHCF) followed by alternating layer-by-layer electropolymerization of polypyrrole-poly(styrene-sulfonic acid) (PPy-PSSA) and PPy-Enzyme (glucose oxidase or lactate oxidase) to a total applied charge density (QT = 50 or 100 mC/cm2 applied in Q = 5, 10 or 100 mC/cm2 increments) were evaluated for their contributions to a biosensor's bioanalytical performance. Single layered PPy-Enzyme (100 mC/cm2) Biotransducers showed a higher sensitivity compared to all multi-layered Biotransducers. An interceding layer of NiHCF at the Pt|PPy-GOx interface improved consistency in PPy-GOx electrodeposition compared to unmodified devices but, measured under self-consistent anodic conditions (0.65 V vs. Ag/AgCl), did not improve sensitivity. Electrochemical Impedance Spectroscopy (EIS) showed that the mediator layer did not change the overall impedance spectra of the Pt microelectrode array when compared to unmodified Pt electrodes. Under anodic test conditions, non-mediator modified devices had a higher sensitivity (0.94 nA/mM) to glucose than the mediator modified devices (0.32 nA/mM).
-
Biofabrication Using Pyrrole Electropolymerization for the Immobilization of Glucose Oxidase and Lactate Oxidase on Implanted Microfabricated Biotransducers
Bioengineering, 2014Co-Authors: Christian N. Kotanen, Olukayode Karunwi, Anthony Guiseppi-elieAbstract:The dual responsive Electrochemical Cell-on-a-Chip Microdisc Electrode Array (ECC MDEA 5037) is a recently developed electrochemical transducer for use in a wireless, implantable biosensor system for the continuous measurement of interstitial glucose and lactate. Fabrication of the biorecognition membrane via pyrrole electropolymerization and both in vitro and in vivo characterization of the resulting Biotransducer is described. The influence of EDC-NHS covalent conjugation of glucose oxidase with 4-(3-pyrrolyl) butyric acid (monomerization) and with 4-sulfobenzoic acid (sulfonization) on biosensor performance was examined. As the extent of enzyme conjugation was increased sensitivity decreased for monomerized enzymes but increased for sulfonized enzymes. Implanted Biotransducers were examined in a Sprague-Dawley rat hemorrhage model. Resection after 4 h and subsequent in vitro re-characterization showed a decreased sensitivity from 0.68 (±0.40) to 0.22 (±0.17) µA·cm−2·mM−1, an increase in the limit of detection from 0.05 (±0.03) to 0.27 (±0.27) mM and a six-fold increase in the response time from 41 (±18) to 244 (±193) s. This evidence reconfirms the importance of biofouling at the bio-abio interface and the need for mitigation strategies to address the foreign body response.
-
Characterization of a Wireless Potentiostat for Integration With a Novel Implantable Biotransducer
IEEE Sensors Journal, 2014Co-Authors: Christian N. Kotanen, Anthony Guiseppi-elieAbstract:Wireless potentiostats are being developed and commercialized for use in the development of implantable electrochemical biosensors for the monitoring of physiological markers in a wide range of pathologies. The merits and drawbacks of the Pinnacle 8151 dual potentiostat were investigated for use with a novel implantable Biotransducer, the dual responsive microdisc electrode array (MDEA 5037) of ABTECH Scientific. The potentiostat was evaluated with R and RC dummy cells and with MDEA transducers modified with polypyrrole-poly(2-hydroxyethyl methacrylate) electroconductive hydrogels that were all qualified by calibrated ac impedance spectroscopy. In a laboratory setting, the 8151 potentiostat maintained a steady and unbroken signal as far away as 75 ft (23 m), and when unobstructed, up to 100 ft (30 m). The error between the two channels was determined to be 6.4 (±0.3)% and 0.7 (±0.1)% for resistor-capacitor dummy cells ( RC=nominally 10 MΩ and 1 μF) and resistor dummy cells (R=nominally 10 MΩ), respectively. The intra-channel variability was judged to be too large for exacting analyte determinations.
-
Enzyme Biotransducers formed from conductive electroactive polymers
2013 IEEE SENSORS, 2013Co-Authors: Guneet Bedi, Christian N. Kotanen, Olukayode Karunwi, Amanda Nguyen, Ferhat Bayram, Brian Hudson, Yu Zhao, Anthony Guiseppi-elieAbstract:Three types of Biotransducer devices were studied: an enzyme Field Effect Transistor (Enz-FET), an interdigitated microsensor electrode (IME) array for impedimetric detection, and a microdisc electrode array for amperometric detection. Each device type was microlithographically fabricated from a pattern of sputter deposited metal (10 nm Ti/W| 100 nm Pt or Au) on an insulating substrate that was either glass or oxidized p-type silicon. Insulating regions were fashioned from Si3N4 and the gate dielectric of the FET was a SiO2 layer of 100 nm thick spin-on glass. For each Biotransducer device type, the enzyme glucose oxidase (GOx) was immobilized using a process of electropolymerization of pyrrole (0.8 V vs. Ag/AgCl) in the presences of glucose oxidase (1 mg/ml) in deionized water to achieve a total of 100 mC/cm2. The dose-response characteristics of each of the Biotransducers were tested in muta-rotated glucose solutions (PBS 7.2) at RT that ranged from 0.0 mM to 20 mM. The sensitivity (m=slope), linear dynamic range and limits of detection [3(SDblank/m)] were calculated from replicate measures of the dose response curve.
-
Wireless System with Multianalyte Implantable Biotransducer
Security and Privacy for Implantable Medical Devices, 2013Co-Authors: Christian N. Kotanen, Anthony Guiseppi-elieAbstract:Wireless potentiostats are being developed and commercialized for use in the development of implantable electrochemical biosensors for the monitoring of physiological markers in a wide range of pathologies. The merits and drawbacks of the Pinnacle Technology 8151 dual potentiostat are investigated for use with a novel implantable Biotransducer, the dual responsive MDEA 5037 of ABTECH Scientific. In a laboratory setting, the 8151 potentiostat maintained a steady and unbroken signal as far away as 75 ft (23 m) and, when unobstructed, up to 100 ft (30 m). The percentage error between the two channels was determined to be 6.4 (±0.3) and 0.7 (±0.1) for resistor-capacitor dummy cells (RC = 10 MΩ and 1 μF) and resistor dummy cells (R = 10 MΩ), respectively. The intrachannel variability may be too large for exacting analyte determinations.